Kerner is a licensed psychotherapist and nationally recognized sexuality counselor who specializes in sex therapy, couples therapy and working with individuals on a range of relational issues. Ian is regularly quoted as an expert in various media, with recent appearances on The Today Show, The Dr. Oz Show, and NPR. He lectures frequently on topics related to sex and relationships, with recent[when?] presentations at New York University, Yale, Princeton and the Ackerman Institute. Kerner is a Clinical Fellow of the American Association of Marriage and Family Therapists and is certified by the American Association of Sexuality Educators, Counselors and Therapists.

Kerner is the author of She Comes First: the Thinking Man's Guide to Pleasuring a Woman. Amy Sohn in the New York Times called this book "the Encyclopaedia Britannica of the clitoris." Sohn went on to say that "...with a cool sense of humor and an obsessive desire to inform, he encourages men through an act that many find mystifying." [2]She Comes First was selected by both Amazon.com and Borders as a "Best of 2004" non-fiction title and has been translated into numerous[vague] languages. The companion book He Comes Next: the Thinking Woman's Guide to Pleasuring a Man was published in 2005. Kerner also wrote Be Honest, You're Not That Into Him Either.

Kerner lectures in the US on a variety of subjects related to sex and relationships. Appearances include: The Organization of Women Leaders at Princeton University, human sexuality classes at Indiana University, the W Hotel's Wonderland Series, the 92nd Street Y in New York City, and Sex Week at Yale University.